Derive the first equation of motion.

Step 1: Acceleration

1. A change in velocity with respect to time is called acceleration.

Step 2: Deriving equation

Then, $a=\frac{v-u}{t}$ here v is the final velocity and u is the initial velocity and t is time.

Rearranging the above equation we get

$$\begin{gathered} at=v-u \\ \Rightarrow v=u+at \end{gathered}$$

Hence, $v=u+at$ is the first equation of motion.